Chorionic villus sampling (CVS) has become a widely-used technique for prenatal genetic diagnosis, even though it was still considered experimental as recently as 1992. The test is used to identify chromosome and biochemical conditions such as Tay-Sachs disease, the sex of the fetus and certain inherited conditions. Although it was at first hailed as a very safe procedure, reports soon began to surface about CVS possibly causing limb defects in babies.

Because of uncertainties about whether one type of prenatal test may increase the risk of fetal limb and facial abnormalities, FDA has required the manufacturer to add a warning about the risk to the test's patient labeling.

FDA is also requiring the test, called chorionic villus sampling (CVS), to carry revised physician instructions specifying that the test should only be done after the 10th week of pregnancy. Some research suggests this may reduce the risk.